During the use of absorbent products such as nappies, sanitary towels or incontinence pads, it is frequently the case that various sorts of bodily discharges such as urine, loose stools, menstrual fluid or other bodily fluids which come into contact with that surface of the product which faces the wearer are not directly able to penetrate through the liquid-permeable surface layer of the product and into the absorbent body of the product. There is then a risk that discharged liquid will begin to move on top of the liquid-permeable surface layer and may then run out past the edges of the product. The liquid movements can take place in any direction on top of the liquid-permeable surface layer. Liquid movements in the transverse direction of the product are particularly worrying because only a relatively small liquid movement in the transverse direction involves the liquid running outside one of the long sides of the product with the result that articles of clothing, bedclothes, seat cushions and other surrounding articles are easily soiled by the discharged liquid.
Many different attempts at improvements have been made in order to eliminate this problem. It may be mentioned, for example, that the liquid-permeable surface layers have been improved considerably with regard to their capacity for allowing various types of bodily fluid to pass through quickly and thus for preventing the liquid having time to move any further on top of the surface before penetration through the surface layer takes place. The most common attempts at preventing bodily fluid running outside the long sides of the absorbent product have consisted in trying in different ways to create various forms of barrier in association with the longitudinal edges of the product in order to prevent the running liquid from passing the longitudinal edges of the product and ending up outside the product and causing leakage. Various types of barrier solution have been described.
Absorbent products having side flaps with a barrier function are described in, for example, patents EP 0,091,412, U.S. Pat. Nos. 3,860,003, 4,579,556 and 5,032,121. These patents describe absorbent products with side flaps which consist of the two covering layers of the product together with pretensioned elastic systems arranged between the covering layers. When these pretensioned elastic systems are contracted, this means that the materials in the side flaps are also contracted and are thus brought into an upwardly directed configuration in relation to the plane of the respective covering layer. In their raised configuration, the raised side flaps constitute barriers which seal effectively against the thighs/groins of the wearer.
International patent application WO 98/08474 describes another form of absorbent product with elasticated side flaps. The elasticated side flaps according to WO 98/08474 are folded in over the liquid-permeable covering layer of the product and are fixed to the liquid-permeable covering layer. The result is an absorbent product with upwardly directed barriers which are inclined in towards the longitudinal symmetry line of the product.
U.S. Pat. No. 4,904,251 describes an absorbent product with upwardly directed barriers extending in the longitudinal direction of the product between the longitudinal edges of the absorption body and the longitudinal outer edges of the side flaps. The upwardly directed configuration is brought about for this type of barrier also by pretensioned elastic threads, bands or the like being contracted together with the barrier materials.
Absorbent products containing double elasticated barrier systems are described in U.S. Pat. No. 4,695,278. This patent describes absorbent products comprising both elasticated inner barriers and elasticated side flaps. The inner barriers extend in the longitudinal direction of the product and adopt an upwardly directed configuration in relation to the plane of the liquid-permeable covering. The side flaps, which consist of both the covering layers of the product, have also been provided with various types of pretensioned elastic system which, when contracted, are drawn together and then also contract the side flaps which thus also adopt an upwardly directed configuration which provides a good barrier function. The advantage of this solution is that bodily fluids which run on top of the liquid-permeable surface layer have to pass two barriers before leakage occurs. The problems of this double-barrier solution are not principally associated with leakage prevention but rather with material cost, manufacture and comfort.
Double elasticated barrier systems mean that, before everything else, the costs of the elastic materials rise dramatically. Costs incurred for special types of fixing adhesive for fixing the elastic materials, which are often difficult to fix, also increase if use is made of double elastic systems. Fixing elastic systems using adhesive is currently the most common fixing method and, because fixing elastic materials is complicated, extremely expensive adhesive qualities in great quantities must in most cases be selected. Moreover, extra elastic materials and adhesive mean that the environment-friendliness of the absorbent article is impaired.
As far as the manufacture of absorbent articles is concerned, which has to take place at high rates in order to achieve satisfactory profitability, each new material component of the absorbent article also means that the number of process steps in the manufacturing process increases, which in turn means that the number of places in the manufacturing machine where there is a risk of machine stoppage occurring increases. Starting up/restarting a more complex manufacturing machine which is to manufacture an article containing a number of starting materials is also more difficult and more time-consuming than starting up a simpler machine for manufacturing a less complex article containing fewer material components. The number of substandard products which lack one or some material components also increases with a larger number of component materials, and these products have to be rejected, which reduces the profitable use of raw materials. Furthermore, a larger number of material components of elastic type, which are normally supplied to the production machine in roll form, means more roll changes, which requires a higher manning level for production in the machine with maximum effectiveness. New material components which are added to the absorbent article also mean, as mentioned above, that the manufacturing machine becomes more complex, with increased maintenance costs as a result.
Elastic components applied in association with projecting free edges on the absorbent product, such as on the free edge of the inner barrier or on the outermost edge of the side flap, are moreover unfortunate from the point of view of comfort because the free edge is both folded and stiffened, with an increased tendency to chafe as a result. The elastic system itself and the extra adhesive which is normally required for anchoring the elastic system result in a considerable increase in the stiffness of the elasticated edge, which often causes the wearer irritation problems. The irritation problems are particularly great because the purpose of the elastic is, by means of its elastic capacity, to press against the thigh sides or against the groins of the wearer so as to provide sealing.